While old trees can be found in a few other parks in Seattle, the
Magnificent Forest, covering about 120 acres on the northern 2/3 of the
Bailey Peninsula, is the largest stand of old trees in the city. Old
growth forest is characterized by trees of various ages including large
trees >250 years old, by a multi-layered canopy, by standing snags
and by large down logs. The Magnificent Forest has these features, but
for an old growth forest it is young, with many trees less than 200
years old.

The dominant tree of the Magnificent Forest is Douglas fir. Western red
cedar, bigleaf maple and madrona are also well-represented. Western
hemlock is found mainly toward the northern end of the peninsula. The
shrub understory is composed largely of salmonberry, thimbleberry,
elderberry, Indian plum, hazelnut, sword fern, and Cascade Oregon grape.
The abundance of madronas, both in the forest and in the developed
southern part of the park, indicates a well-drained, relatively dry
site. The Bailey Peninsula is one of the few sites in Seattle where
bedrock reaches the surface. The shallow soils overlaying the bedrock
combined with the topography of the peninsula contribute to good
drainage and dryness.

Forest Succession

15,000 years ago the Puget Sound region was covered by the Vashon
glaciation. After the ice receded 13,650 years ago, herbaceous plants
first became established on the barren glacial debris, and it took about
1,000 years before trees (Douglas firs) became established.

Douglas fir can become established in open sunny locations, but does not
grow well in shade, so shade-loving hemlocks and cedars theoretically
succeed Douglas fir forests. Drier habitats, however, do not support
hemlock and cedar well. In such locations, Douglas fir succeeds itself,
depending on natural tree death, storms and wildfire to create openings
where seedlings can become established. Tree ring dating on trees cut
early this century indicated that the Magnificent Forest was severely
burned in the 1490s. The relatively young age of many trees and the
presence of burn scars on older trees suggest that it also burned in the
early 1800s.

Fungi and the Forest

Conifers and many other trees form associations with mushrooms and other
fungi in the soil. Tree roots become coated with fungal mycelium,
inhibiting the growth of the root hairs that absorb water and nutrients.
This does not harm the trees, but rather the fungal coating increases
the
efficiency with which they can absorb nutrients. The fungi in turn
receive sugars from the trees. This mutually beneficial relationship is
known as a mycorrhizal association. Different mushrooms and trees vary
in the specificity of their choices for mycorrhizal partners. The same
tree may have different associated fungi at different stages of its
life. Fungal mycelium may connect adjoining trees in a nutrient web.

In addition to their crucial role in forming mycorrhizal
associations, fungi perform another indispensable task in forest
ecology. The decay of dead wood is carried out mainly by fleshy fungi.
While woodpeckers, bark beetles and carpenter ants all contribute to the
breakdown of wood, the actual decay is done almost exclusively by
wood-inhabiting mushrooms, especially the polypores. These mushrooms
have pores rather than gills and their fruiting bodies are often
persistent on dead wood, adding a new layer of pores each year. Although
decay is slow in northwest forests, the role of these fungi in
returning the nutrients locked up in dead wood to the forest ecosystem
is a vital one.

The Magnificent Forest is too small and isolated to support many of the
animals, plants and fungi that characterize larger old growth forests,
but it does provide shelter to mountain beavers, raccoons, deer mice,
western screech owls, bald eagles, pileated woodpeckers and dozens of
other bird species. Insects, spiders, and other invertebrates abound.
The forest was home to mink until they were trapped in 1941, to deer
until 1952, and to Douglas squirrels at least until the 1960s. The
forest shores are visited by muskrats, beavers, river otters, red-eared
turtles, and many kinds of fish and waterfowl.

The Lakeshore

Unlike the forest, the lakeshore is very young. The present
shoreline was created in 1916 when the Montlake cut of the Lake
Washington Ship Canal was opened, lowering the lake by about 9 ft.
Subsequently the shoreline was graded to make the loop road. Ornamental
trees such as Lombardy poplar, cherries, catalpa, and others were
planted in many places along the shore, but most of the shoreline
appears to have revegetated naturally. Both the forest and the marshy
areas drained by the lake lowering probably served as sources of seeds.
Douglas firs and thimbleberries came from the forest, and Oregon ashes,
Sitka willows, rushes, sedges, cattails, and others probably came from
nearby wetlands. The new shores also provided opportunity for invasive
species such as Himalayan blackberry, reed canary grass, and yellow
loosestrife.

The Garry Oak Prairie

Garry oak with oak apple galls, produced by tiny
parasitic stingless gall wasps. The galls serve to protect and feed the
gall wasp larvae and do not cause measurable harm to the oaks.

Clark’s Prairie

In 1852 E. A. Clark and John Harvey, fresh from
the California gold rush, staked adjacent claims and built a cabin just
south of here in an area that came to be called Clark’s Prairie. They
probably picked this spot because the natural oak prairie or savanna
here required less forest to be cleared in order to farm. Evidence of
Clark’s Prairie can still be seen in the Garry oaks found in Seward Park
and Martha Washington Park, in the local street names Oakhurst and
Oaklawn, and in the fire-adapted plants associated with oak ecosystems
that are found on the south side of Pinoy Hill in front of you.

Fire Ecology

Oak prairies and savannas are the most
threatened ecosystems in western Washington, because cities have been
built over them and because of a century of fire suppression. Native
Americans maintained these ecosystems against the encroachment of
Douglas-fir forests by burning them. Thick-barked Garry oak and other
fire-adapted prairie plants survive fires that kill Douglas–firs and
hemlocks. Native Americans encouraged prairies because they were rich in
game and edible plants, including acorns. An 1861 land survey from this
area mentions oaks and describes “deadenings” that suggest active
burning by the local Lake People, who may have planted the oaks here.

Fire-Adapted Plants

Camas, distinguished by its blue
flowers in spring, was a major prairie food plant for native peoples
throughout the west. Camas bulbs were boiled, roasted in pits, or dried
and ground into flour for making cakes.

Snowbrush is a fire-adapted
species that requires fire to germinate its seeds. Extremely rare in
Seattle, a few snowbrush are found scattered on the hillside above you.
Snowbrush can fix nitrogen like lichens, legumes or alder, giving it an
advantage in re-colonizing burned-over areas after a fire.

Snowbrush or sticky laurel is
easily recognized by its sprays of white flowers and its evergreen
sticky leaves with three prominent veins.

Poison-oak is uncommon in
Seattle but abundant on the south side of Pinoy Hill. It is a
fire-adapted species that is unrelated to oaks, but shares their
habitat. While most people are highly allergic to it, the California
Indians used it in basketry without ill effects. The shiny leaves of
three leaflets turn brilliant crimson in the fall.
Poison-oak:
“Leaflets three, let it be
Berries white, poisonous sight”

Prairie Restoration

In 2007 the Friends of
Seward Park received a grant from the Washington Native Plant Society to
help restore the understory of Clark’s Prairie in Seward Park, both for
habitat enhancement and for public education about Washington’s oak
ecosystems. The Friends partnered with Seattle Parks and Recreation,
Seward Park Environmental and Audubon Center, sixth grade classes from
Orca K-8 School and other volunteers to plant over 200 prairie plants
including camas, chocolate lily, Henderson’s
shooting star, and Roemer’s fescue. The restored prairie is a focus of
educational programs by the Seward Park Environmental and Audubon
Center, including long-term monitoring for plant survival and reseeding,
and for the return of birds, butterflies, garter snakes, and other
prairie animals.